Re: [RFC PATCH v1 09/28] x86/efi: Access EFI data as encrypted when SEV is active

From: Tom Lendacky
Date: Thu Sep 22 2016 - 15:05:44 EST

On 09/22/2016 12:07 PM, Borislav Petkov wrote:
> On Thu, Sep 22, 2016 at 05:05:54PM +0200, Paolo Bonzini wrote:
>> Which paragraph?
> "Linux relies on BIOS to set this bit if BIOS has determined that the
> reduction in the physical address space as a result of enabling memory
> encryption..."
> Basically, you can enable SME in the BIOS and you're all set.

That's not what I mean here. If the BIOS sets the SMEE bit in the
SYS_CFG msr then, even if the encryption bit is never used, there is
still a reduction in physical address space.

Transparent SME (TSME) will be a BIOS option that will result in the
memory controller performing encryption no matter what. In this case
all data will be encrypted without a reduction in physical address